This invention relates, in general, to microwave hybrids for use in Monolithic Microwave Integrated Circuits (MMIC) technology, and more specifically, to 90 degree broadband hybrids.
Broadband 90 degree hybrids are basic components in analog microwave systems and are used when a RF input signal is to be divided into equal amplitude signals that differ in phase by 90.degree.. The split signals are directed to two output ports.
Current microwave 90 degree hybrids are generally made using distributed methods, such as the Lange or De Ronde couplers. These, and other current methods for developing 90 degree hybrids, are not easily adapted to use in MMIC technology. MMIC circuits utilize gallium Arsenide (GaAs) which only allows for extremely small circuit areas, and cannot utilize ferrite in construction of the circuit. Therefore, the current technology is not usuable in MMIC's, or is limited to very high frequencies (above 25 GHz). Furthermore, existing MMIC lumped element 90 degree hybrids have narrow bandwidths (less than 5%).